Process of making boron nitrid.



- Ho Drawing.

GEORGE WEINTBAUB, OF Lm,

comm,

MASSACHUSETTS, ASSIGNOB TO GENERAL ELECTRIC A COBPUELTION OF NEW YORK.

PM BAKING B08017 NITBID To all whom it may concern:

Be it known that I, Grouse Wmrrrasun, a citizen of the United States, residing Lynn,inthecountyofEsex,Stateof sachusetts, have invented certa n new and useful Improvements in Procemns of Mak mg ioron Nitrid, of which the following is a xpecification. t

Various rocemes for nltl'ld of boron are escribed in the chemical literature. However, the percentage yield obtainable by these methods is not only poor but the nitrid thus produced is not chemically stable. For example, it 1s slowly decom by hot water, forming home anhydrid and-ammonia. It also quite readily oxidizable even at relatiyely low temperatures. Its chemical instability may due either to its hysical state or to associated impurities. c of boron mtnd is more marked in the P not of certam reactions than others, but to my best knowledge the above holds true of all boron nitrld heretofore roduc'ed.

I have r scovered that when compounds of boron, such as boric anhydrid, borax, etc, are heated in the presence of a cyanogen compound, such as a cyanid or a ferrocyanid, at a temperature high enough to quickly volatilize all products of the reactlon, other than boron nitrid, that a 'eld of very pure, stable nitrid of boron is produced.

The reaction between boric acid and cy anidsisnotanew one. Ithasbeenusedby Balmainandisdescribedintextbooks. The reaction was carried out in an ordinary gas furnace and the products of the reaction, which are of various natures including carbonates and cyanates, had to be washed out with water and the product then dried. Due to the low temperature of the reaction the boron nitrid is of alpw degree of stability and snag the wwfififisznd decomposed to a large degree, the yiel is not satisfactory.

I have discovered that if the reaction is carried out at a temperature at which the cirbonatas and cyanates as well as the excess of ham or bone anhydrid used are easily volatile, that all the submances with the ex. t ipxh'ouofboronnitridarevolatilizedso specification of Letters ratent.

Application fled i'ehrualy 3, 1913. Serial In. 745,820.

nofurthertmaunentisnecemaryand Patented Apr. 13, 1915.

that the boron nitrid obtained, due to the high temperature of the reaction, is of a high d o stability. 11 carrying out my invention, one part of boric anhydrld, borax, or other boron compound and one to two parts of potassium or sodium cyanid, or a chemically equivalent amount of another cyanogen compound are finely powdered and mixed,as by tumbling in a ball mill. The mixture is placed in a graphite crucible or other refractory container and brought rapidly to a temperature of about 2000 C. in a furnace, which will allow the escape of fumes, such asan electric resistance furnace. Preferably the furnace is preheated to the reaction temperature. Copious vapors are evolved at once. The fumes, when using a cyanid, consist largely of the carbonate of the metallic constituent, for example, sodium carbonate, and are substantially free from cyan or.cyanid, so that ,the operation is peiz tly safe, even though no special revision is made to carry away the fumes. 0 reaction is allowed to continue until no more fumes are given of. This. time may be as short as a. few minutes, depending on the uantit used. About and upward theoretica yield of white, stable boron nitrid is produced.

I make no claim herein on stable boron nitrid as an article of manufacture, this ma terial be' claimed in a co nding application, Seri No. 745,819, fllfid concurrently herewith.

What I claim as new and desire to secure by Letters Patent of the United States, is:--

1. The process of m boron nitrid which consists in heating a mixture of boron run-containing material and a cyanid to a temperature at which reaction occurs and the products other than boron nitrid are volatilized.

2 The process of making boron nitrid whlch consists in heating a mixture of boron compound and a cyanogen compound to a temperature at which reaction occurs and substantially all by-products are volatilized.

3. The recess of making pure, stable .boron, nitri which consists in heating a mixture of boric anhydrid and a cyanidto a temperature ofabout 2000" C. until no more fumes are evolyef.

t. A process 0 making pure stable boron nitrid which consists in heating a mixtuge In witness whereof, I have hereunto set comprising about one part of boric anhygh'ld my hand this thirty-first day of January, and about one to two parts of potassmm 1913.

cyanid rapidly up to a temperature of about GEORGE WEINTRAUB. 2000 C. until no fumes are given off under Witnesses:

conditions allowing the free escape of the Joan A. MCMANUS, Jr.,

fumes. FRANK G. Hu'rm.

Home: at this patant may h cbhlned for in cents each. by addressing the Commissioner of Patents, Washington, D. 0.

It is hereby certified that in Letters Patent No. 1,135,232,gmnted April 13 1915,

upon the application of George Woinbl'auh, of Lynn, Massachusetts, for :m improvement in Processes of Making Boron Nitrid," an error appears in the printed SllOtification requiring correction as follows: Page 1, line 92, strikrout the syllable ron before containing; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Olfice.

Signed and sealed this 11th day of May, A. D., 1915.

[SEAL] R. F. WHITEHEAD,

Acting Commissioner f Patents. 

